This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the described embodiments. Accordingly, it should be understood that these statements are to be read in this light and not as admissions of prior art.
The present disclosure relates to methods for interpreting nuclear magnetic resonance (NMR) data. In particular, but not by way of limitation, this disclosure relates to relates to interpretation of NMR data by simultaneously detecting more than one resonant nucleus.
Spatially resolved measurements have been applied to monitoring oil recovery from small rock samples in the laboratory, enabling, for example, rapid screening of enhanced oil recovery (EOR) chemicals (surfactants, polymers). Low-field 1H (proton) NMR is conventionally used for these studies to (a) provide consistent physics of measurement to downhole tools and (b) minimize the effect of magnetic susceptibility contrast on the measurements. NMR has a significant advantage over X-ray computed tomography (CT) in these measurements: the ability to discriminate fluid phases (oil, gas, brine) based on inherent properties of the fluids (spin relaxation time, diffusion coefficient). However, there are cases where these inherent fluid-phase contrast mechanisms are insufficient to discriminate the phases, e.g., mud filtrate invasion in pre-salt carbonate formations.